Q- If in exam 45% student fail in Maths, 30% student in English and 20% in both exam. What percantge of students pass in both subject ?

Ans:- In this question 45% student fail in maths and 30% student fail in English and 20% student in both exam. It means total 20% of student fail in both Math and english. So what you have to do you just subtract 20% from both maths and english fail students. which comes like this.

45-20=25 (it means 25% student only fail in maths)

30-20=10 (it means 10% student only fail in english)

and total percentage of student fail in both exam are 20%

from this we now say like this

total percentage of student fail are 25+10+20=55%

Therefore, total student pass in both subject are 100-55=45% .

Trick- 100-(Maths fail + English fail - both subject fail student )